Process for the optical brightening of



PROCESS FOR THE OPTICAL BRIGHTENING OF MATERIALS OF POLYESTERS FranzAckermann, Binningeu, and Adolf Emil Siegrist, Basel, Switzerland,assignors to Ciba Limited, Basel, Switzerland, a Swiss firm w NoDrawing. Application February 6, 1956 Serial No. 563,446

Claims priority, application Switzerland February 15, 1955 6 Claims. or.117- 435 This invention is based onthe observation that materials ofpolyesters, especially polyester fibers, can be optically brightenedwhen such a material is treated with a non-quaternary compound having nodyestuff character, which is colorless or only slightly colored,contains no acid salt-forming or water-solubilizing group, which insolution or on a substratum fluoresces green-blue to violet in daylightor ultra-violet light and which contains two five-membered heterocyclicrings, each of which consists of two adjacent carbon atoms which are atthe same time ring members of a benzene ring, a nitrogen atom attachedto one of the two mentioned carbon atoms, a hetero atom having an atomicnumber of at least 7 and at most 8, viz. an oxygen, or nitrogen atomattached to the other of the two mentioned carbon atoms and a carbonatom attached to both hetero atoms, the two latter carbon atoms of thetwo heterocyclic rings being attached together by way of an ethylenebridge.

The material to be improved by the use of the present process can existin any stage of processing, it being obviously advantageous to treat itin the described manner at a stage when all other treatments have beencompleted which would have the effect of removing again the agent usedaccording to the invention or would have an unfavorable etfect upon it.The agents used can for example be added to the material to be improvedeither before or during the shaping thereof. Thus they can be added tothe moulding mass to be used in the manufacture of foils or shapedbodies or can be dissolved or finely distributed in a spinning massbefore the spinning thereof.

The present process has proved to be of especial advantage for theimprovement of textile fibers of the specified constitution. As fibersto be treated, such of polyesters of terephthalic acid are especiallyconcerned. Staple fibers or also monofilaments can be used, for examplethe products obtainable under the names Dacron and Terylene.

The compounds used according to this invention for the improvement ofthe specified materials must satisfy the requirements set forth in theirabove-description. They must contain no acid salt-forming orwater-solubilizing groups, that is to say no sulfonic acid or carboxylicacid groups. Moreover, they must at most be only slightly colored andmust have no dyestufi character, i. e. they should not dye the materialunder treatment when applied in the customary concentrations. Thecompounds have as a rule basic character and can be used in'the presentprocess either as free bases or in the form of salts which are capableof the formation of the free bases. As above specified, however, the useis excluded from the present process of the quaternary salts obtainablefrom these compounds (imidazolium, oxazolium' or thiazolium compounds).

As stated above the compounds used in the improvement process of thisinvention contain two S-membered heterocyclic-rings and each of theserings, which as re- States Patent gards chemical constitution arecomprised within the ice definition azole rings, possesses a structurewhich corresponds to one or other of the following formula In both ringsthe two adjacent carbon atoms are at the same time ring members of abenzene ring which may contain further substituents. Moreover, the tworings are attached together through the carbon atom between the twohetero atoms by way of an ethylene bridge.

Accordingly, in the present process compounds are'used of the formula(a) B\ Y A A o-oH=oH-o V A I in which A indicates abenzene radicalcondensed with the hetero ring as shown by the valence bonds, B is anoxygen atom or the group and D are nitrogen atoms of which each is alsofurther attached to-a low molecular alkyl radical, for example such aradical containing at most six-carbon atoms, but preferably an ethyl ormethyl group.

Since the double bonds of the radical Act the abovementioned generalformulae are in conjugation with the double bond of the heterocyclicring, by suitable substitution of this radical an increase of thefluorescence can also be attained. As substituents in the radical Athere are concerned alkyl, alkoxy, alkylamino or acylamino groups orhalogen atoms. I

Thus, for example, valuable results can also be achieved with thecompounds of the formula Illa it A1. bQ/oqzrhon-ofi in 3azfl-di-[benzoxazolyl-(Z)J-ethylenes of the Formula 3 whose benzeneradicals A are substituted by low molecular alkyl groups, particularlymethyl groups which are preferably in the S-positions of the benzoxazoleradicals.

The compounds to be used in the present process are known in largenumbers and others can be prepared by customary methods known per se.

If it is a question of improving textile fibers by the present processwhich can exist as staple fibers or monofilaments, in the crude state orin the form of yarns or fabrics, this operation is conducted withadvantage in an aqueous medium in which the compounds to be used aredissolved or suspended. If desired dispersing agents can be added in thetreatment, for example, soaps, polyglycol ethers of fatty alcohols orfatty amines, cellulose sulfite waste liquor. or condensation productswith formaldehyde of naphthalene sulfonic acids which may be alkylated.

It'is of particular advantage, especially when the treatment of thefibers is exclusively for the purpose of improving the opticalproperties, to work in neutral, weakly alkaline or acid baths. It islikewise of advantage if the treatment takes place at elevatedtemperature, for example at the boiling temperature of the bath or inthe neighborhood thereof (about 90 C.). It is surprising that thecompounds of the composition set forth above possess a good atfinity forthe fibers and can be fixed thereon in a similar manner to dyestufis. Inthis connection it may be remarked that in the case of these syntheticfibers many optical improving and brightening agents which are of goodapplicability for other fiber materials, cannot be used for the reasonthat in this case they cannot be fixed on the fiber or do not give riseto the desired effect. The fastness to light of the materials treatedaccording to the present process is also good, the effect persistingeven after long exposure to light.

The quantity of the improving agent to be used, calculated on thematerial to be treated, can vary within wide limits. Even with verysmall quantities, in some cases, for example, of 0.01 percent, adistinct and permanent effect can be attained. Although quantities ofmore than about 3 percent are in general not disadvantageous, they offerno advantages compared with the normal quantities.

As indicated above, the present process can advantageously be combinedwith other processing methods. Thus the compounds to be used accordingto the present invention can' also be applied as follows:

(a) In admixture with dyestuffs or as additions to dyebaths or printing,discharge or reserve pastes. Further also for the after-treatment ofdyeings, prints or discharge prints, especially in the soaping process.Thus, for example, the polyester fibers can be simultaneously dyed andimproved as regards optical properties if they are treated according tothe present process, advantageously in the presence of a dispersingagent and dyed by the dispersion method, using as dyestuffs coloredcompounds which possess the anthracene structure and which in additioncontain at least one nuclear-bound oxo group, at least one hydroxylgroup or a non-water-solubilizing, sulfur-containing substituent and inwhich the number of any basic, nitrogen-containing groups present is atmost equal to the number of the hydroxyl groups and sulfur-containingsubstituents. As examples of such compounds may be mentionedl-hydroxy-anthraquinone, 1-amino-4z5:8-trihydroxy-anthraquinone and 1-amino-4-hydroxyanthraquinone.

(b) In admixture with chemical bleaching agents 0 as additions tobleaching baths.

. (c) In admixture with finishing agents such as starch or syntheticfinishes. The compounds to be used according to the invention can forexample also be added to the baths used for the production of acrease-proof finish. r

(d) In combination with washing agents: The washing agents andbrightening agents can be separately added to the washing baths to beused. It is also advantageous to use washing agents which containbrightening agents admixed therewith. As washing agents are suitable forexample, soaps, salts of sulfonate washing agents, as for example, ofsulfonated benzimidazoles substituted on the Z-carbon atom by higheralkyl residues, also salts of monocarboxylic acid esters of4-sulfophthalic acid with higher fatty alcohols or salts of fattyalcohol sulfonates, alkylaryl sulfonic acids or condensation products ofhigher fatty acids with aliphatic hydroxyor amino-sulfonic acids.Non-ionic washing agents can also be used, for example polyglycol etherswhich are derived from ethylene oxide and higher fatty alcohols, alkylphenols or fatty amines.

The washing agents of the above specified type can also contain thecustomary washing agent additions, such as alkali metal carbonates,phosphates, pyrophosphates, polyphosphates, metaphosphates, silicates,perborates or percarbonates, so long as the brightening agents arecompatible with such additions. It is also possible to prepare washingagents which consist solely or for the most part of inorganic compoundsof cleansing effect and the brightening agents. The production of themixtures of the washing agents and optical brightening agents takesplace in a simple manner by mixing and/or grinding of the componentstogether. In this case it may be of advantage to use one or the othercomponent in the dissolved or molten condition for the purpose offacilitating distribution.

In general a small addition of the optical improving agents to thewashing agents suffices. There are concerned, for example, quantities of0.1 to 5 percent calculated on the washing agent. Also smallerquantities, for example, 0.01 percent or even less can be added. Alsomixtures with other known brightening agents can be used. The washingagents are used in the customary washing processes. In this mannermaterials to be cleansed can be simultaneously washed and brightened.

When the present process is combined with other treatment or improvementmethods, for example those set forth above under (a) to (d), thecombined treatment advantageously takes place with the aid of suitablyconstituted preparations. These stable preparations are characterized bya content of compounds of the type specified above, especiallyderivatives of oxazole, and also further textile treating agents, forexample dyestuffs, chemical bleaching agents, finishing agents orespecially washing agents.

Further valuable preparations which are primarily suited for theimprovement of polyester fiber as regards optical properties alone, thatis to say without additional treatment according to (a) to (d), aredistinguished by the fact that they contain in addition to the compoundsof the composition initially described above also acidreacting,preferably solid substances. As examples of such substances may bementioned sodium bisulfate, tartaric acid and urea nitrate.

The following examples illustrate the invention, the parts andpercentages being by weight unless otherwise stated:

Example 1 Polyester fabrics are treated for 20 minutes at C. in a bathratio 1:40 with 0.02 percent of ucfldi-[benzoxazyl-(2) J-ethylene of theformula S thenrinsed and dried. The resulting fabric has a higher whitecontent than the untreated material. If instead of 1 gram of disodiumsulfate, 1 gram of 85' percent formic acid is used, a similar efiect isattained.

I Example 2 V The process is conducted as described in Example 1 butthere is used instead of 0.02 percent ofazp-di-[benzoxazyl-(2)]-ethylene 0.2 percent ofa-[N-hydroxyethylbenzimidazyl (2)] 13 [N methylbenzimidazyl(2)]-ethylene of the formula N /N CCH=CHO omomorr H3 The fabric appearsbrighter than the untreated material. Similar effects are obtained withthe compounds of the following formulae l& CHPCHQNQCHM I Example'j 30parts of 7 ct :fl-di-[N-methyhbenzimidagyh(Z) ]-eth'y1- are are groundto a fine, homogeneous powder in a suitable mixing and gr'indingapparatus with 60 parts of sodium bisulfate and 910 parts of acondensation product from naphthalene sulfonic acid and formaldehyde.

Polyester fibers, for example Terylene, which have been treated in abath ratio of 1:30 for 30 minutes at 80100 C. with 2 percent of thispowder in a bath which contains per liter l-2 cc. of ammonia, thenrinsed and dried, possess a brighter appearance than the untreatedmaterial.v v r If the 60 grams of sodium bisulfate are replaced by 60grams of a condensation product from naphthalene sulfonic acid andformaldehyde or 60 grams of urea nitrate or 60 grams 'of tartaric acid,a product with similar properties is obtained.

:imilar effects are obtained withazfi-di-[N-ethylbenzimidazyl-(Zfl-ethylene.

Example 4 so parts of aiB-di-[N-methyl benzirnidazyl- (2)]:ethy1-en'eare ground to a fine, homogeneous powder with 950 parts oftartaricacid. Polyester fibers,= 'for example Dacron which are treated in a-bathratio. of 1:40 for 30 minutes at -95 C. with 1- percent of the powder ina bath which contains per liter 1-2.cc. of ammonia and 1 gram ofthesodium salt of 2-heptadecyl-N-benzylbenzimidazyl disulfonic acid, thenrinsed 'and dried, possess a brighter appearance than the untreatedmaterial. v

- Byusing instead of 1 gram of the above preparation, 1 gram of a powderwhichcontains instead of the tartaric acid, sodium bisulfate or ureanitrate or another suitable solid substancesoluble in water with an acidreaction, the resulting fabriehas a similar efiect.

Example, 5

A soap is produced which contains 0.3 percent of 2:5di-[5-methylbenzoxazolyl t2)]-ethylene. I

Polyester fibers, for example Tery lenef which have been Washed in theusual way with-thissoap,"have a brighter appearance than}material whichisi only washed with soap. 1

A similar effect is obtained when there is added per liter of washliquor 0.5 grampf active chlorine in the formof sodium hypochlorite'f 7Instead of the soap a washing material ca n be used of the followingcomposition or also synthetic washingagents. Example 6 12 parts ofa:B-di-[5-methylbenzoxazolyl-(2)]-ethylene are worked up to a .finelydispersed paste with l2'parts of an addition-product from, about 30 molsof ethylene oxide to a mixture of saturated fatty alcohols most of whichhave 18 carbon: atoms and 76 parts of water. I

Polyester fibers, for example Dacron, which are treated in a bathratio'of 1:30 for 30 minutes: at 60- C. with 0.2-percent of this pastein a bath which contains per liter 1 cc. of ammonia, then rinsed anddried, possess a brighter appearance than the untreated material. 4 4 iInstead of the above described addition product, other dispersion agentscan also. be used, for example a condensation product from naphthalenesulfonic acid and formaldehyde. The a:S-di-[S-methyl-berixoxazolyL(2)I-ethylene may be prepared as follows: I

76 parts of fumaric acid dichloride are added dropwise to a solution of123 parts of 1-amino-Z-hydroxy-S-methylbenzene in l200'parts of'chlorobenzene with stirring and exclusion of air at 125-130 C. in thecourse of one hour, and the mixture is then maintained at a gentle boilfor 6 hours; The'resulting yellowish condensation product of the formula7 then added dropwise, the temperature being allowedv to drop.Concentrated hydrochloric acid is then added until the reaction is acid.The mixture is stirred for another hour at abouta60 C., the'separatedproduct is filtered off, washed with water until the. filtrate shows aneutral reaction and, if necessary, is There is obtaineda:B-di-[S-methyl-benzoxazolyl-(2)]- ethylene in the form of palecrystals which melt at 292 C. The solution in dioxaneexhibits a bluishfluorescence.

- Example 7 A mixed fabric frompolyester fibers, for example Teryleneand wool is treated in a bath ratio-1:50 for 30 minutes at 60-90 C. with2 percent of the preparation obtained according to Example 3, in a bathcontaining 1 gram of ammonia per liter. a

The resulting fabric has a higher white content than the untreatedmaterial. j

A similar effect visobtained in the case of a fabric consisting ofpolyester fibers, for example Terylene, and polyamide fibers, forexample Perlon.

- Example 8 IOO pa rts of polyester fabric, for are treated for one hourat 60-90 following composition:

example -Terylene, C. in a bath of the Example 9 T erylene fabric isdyed for one hour at 90-95 C. in a bath which (calculated on the fabric)contains:

2% l:4-dimethylamino-anthraquinone and 4% afi-di-[N-methyl-benzimidazolyl-(2) ]-ethylene The goods to liquor ratiois 1:40. After being rinsed and dried the fabric so treated has a puregreenish blue and bluish fluorescent shade.

A fabric dyed in the same manner but without the addition of thedi-imidazole compound is less pure in shade and does not fluoresce.

Example 10 "Ierylene fabric is treated at 80-90 C. in a finishing bathof the following composition: I

1 liter water 20 grams potato starch 1 cc. ammonia 24% 0.5 gram of theproduct described in the first paragraph of Example 6 After squeezingand drying the material thus finished has a brighter appearance thanmaterial which has been finished only with starch.

What is claimed is:

l. A process for the optical brightening of materials of polyesterswhich comprises treating the material with a non-quaternary compoundwhich is free from acid saltforming, water solubilizing groups andgroups imparting dyestuif character, which in solution fluorescesgreen-blue to violet and which corresponds to the formula crystallizedfrom dioxane.

in which A is a monocyclic aromatic radical condensed in the mannerindicated by the valence bonds with the oxazole ring.

2. A process for the optical brightening of polyester fibers whichcomprises applying to said fibers in a finely dispersed state theoptical brightening agent of the formula 3. A process for the opticalbrightening of polyester fibers which comprises applying to said fibersin the presence of a dispersing agent the optical brightening agent ofthe formula 4. A process for the optical brightening of polyester fiberswhich comprises applying to said fibers in the presence of a washingagent the optical brightening agent of the formula 5. A composition ofmatter substantially consisting of a polyester and having incorporatedin it a small quantity of a non-quaternary compound which is free fromacid salt-forming, water solubilizing groups and groups impartingdyestuff character, which in solution fluoresces green-blue to violetand which corresponds to the formula in which A is monocyclic aromaticradical condensed in the manner indicated by the valence bonds with theoxazole ring.

,6. A composition of matter substantially consisting of polyester fibershaving incorporated a small quantity of the optical brightening agent ofthe formula References Cited in the file of this patent UNITED STATESPATENTS H1O CHI 2,463,264 Graenacher Mar. 1, 1949 2,483,392 Meyer Oct.4, 1949 2,488,094 Graenacher Nov. 15, 1949 2,515,173 Ackermann July 18,1950 2,604,454 Ackermann July 22, 1952 2,785,133 Craig Mar. 12, 1957FOREIGN PATENTS 611,510 Great Britain Nov. 1, 1948

1. A PROCESS FOR THE OPTICAL BRIGHTENING OF MATERIALS OF POLYESTERSWHICH COMPRISES TREATING THE MATERIAL WITH A NON-QUATERNARY COMPOUNDWHICH IS FREE FROM ACID SALTFORMING, WATER SOLUBILIZING GROUPS ANDGROUPS IMPARTING DYESTUFF CHARACTER, WHICH IN SOLUTION FLUORESCESGREEN-BLUE TO VIOLET AND WHICH CORRESPONDS TO THE FORMULA